Lubricant seals for ball, needle and other types of bearings are well known in the art. Bearings are typically cylindrical, and therefore have annular end seals that are substantially disposed in a single plane. Each seal tightly fits into a groove or land in the bearing inner and outer races.
In general, bearing seals must be sufficiently flexible to enable the seal to be positioned in the bearing races without permanent deformation. A seal must compensate for any dimensional changes in the bearing produced by its thermal environment. Under all conditions the seal must remain substantially in one plane, and not either bow out from or sag in toward the bearing center. Also, the seal must be as simple as possible in design to reduce manufacturing costs.
Existing bearing seals usually have a composite structure which enables them to have both the required flexibility and rigidity. In general, these composite bearing seals include an annular metal band encompassed by rubber. The metal band provides the rigidity to prevent sagging or bowing of the seal, while the rubber provides the necessary flexibility, especially at the seal's inner and outer edges, where the seal is received by the bearing race grooves or lands. A bearing seal of this type is detailed in U.S. Pat. No. 4,650,195. The seal disclosed therein is an anti-friction seal for a bearing. The seal is a composite of a rigid material with a flexible annular element whose construction is similar to the well known metal rubber metal composite bearing end seal discussed above. Other known bearing seals have a rigid-compliant material composite structure but are additionally characterized by a very complex construction. Note the bearing seal of U.S. Pat. No. 4,309,063 wherein first and second annular members are slideably disposed about one another.
Bearing seals made from a single material include the seal of U.S. Pat. No. 2,038,010. Disclosed therein is a ball bearing sealed by means of a steel sealing ring which is snapped into a groove in the outer bearing race and land formed in the inner race. The sealing ring is characterized by a compressible corrugation which is used to initially position the ring in the bearing. The geometry of the corrugation groove is such that the bearing seal deforms out of the plane of the seal to minimize the permanent deformation which would otherwise occur if the groove was not present when the seal was positioned in the bearing.
The ball bearing seal of the '010 patent is comprised of the same material as the remaining bearing components. Consequently, the seal retains its integrity over a wide range of bearing temperatures. Compensation for thermal expansion is not necessary since the thermal expansion coefficients of the materials used for both the bearing and the seal are the same. The bearing seal taught in the '010 patent would be of little use in those applications where the materials which comprise the bearing and the seal are dissimilar, or where out of plane bearing seal deformation is not acceptable.
In the past, bearing seals have seldom been constructed of only a single material because each material suitable for use as a bearing seal does not simultaneously possess (1) rigidity needed to prevent out of plane deformation, (2) the flexibility needed for strain-free bearing assembly and, (3) the compliance needed to compensate for differences in the expansion rates between the various bearing and seal materials. For example, U.S. Pat. No. 3,810,636 discloses a bearing seal made solely from plastic that is characterized by recesses extending parallel to the seal's major surfaces. The recesses improve the seal flexibility but must also provide more than one sealing surface. The additional seal flexibility is necessary to prevent cracking during assembly with the bearing. The additional surface helps compensate for differences in thermal expansion between the plastic and the metal of the bearing.
Other known bearing seals are often designed for a specific application, such as the bearing seal disclosed in U.S. Pat. Nos. 3,700,297; 2,077,881 and 2,830,858. These and other known bearings are not easily adapted for use with wide range of bearings. Any attempt to utilize these seals with other bearings would, in general, undesirably require bearing manufacturers to modify construction of their bearings to conform with a particular seal. To be successful in the marketplace, a bearing seal must be easily adapted to a wide range of bearings without requiring any changes in the design or manufacture of the bearings themselves.